Patent GB-359026-A (GB)
Title: An improved process and apparatus for converting heavy hydrocarbons into lighter hydrocarbons by cracking and destructive hydrogenation
Filed: 1930-07-15
Abstract: In a process for converting heavy hydrocarbon oils to low-boiling oils the feed oil is passed through a cracking zone 6, which is of the nature of a coil or series of coils, the products are admitted under lower pressure which may be atmospheric to a chamber 3 where the lighter constituents are vaporized, the unvaporized residue is passed through lines 15, 17 to a second cracking coil 18, and the products from this coil are discharged into the vaporizer 3.  Vapours withdrawn at 70 are worked up for gasoline and other fractions.  Part of the residue may if necessary be withdrawn.  Either or both cracking steps may take place in the presence of hydrogen or gaseous hydrocarbons in excess, with or without catalysts.  The cracking or hydrogenation is effected at temperatures from 750-1500 DEG  F. and under pressures of 50-3000 lbs. per sq. in.  The temperature in the lower part of the vaporizer is preferably 600-700 DEG  F.  The vaporizer is provided with a steam injection pipe 14, a heating coil 13 and a cooling coil 12 which is independent of the feed oil.  An intermediate condensate from the vaporizer may be recirculated.  In modifications of the process, (1) the feed oil is cracked or hydrogenated in the coil 6, the products are discharged into the vaporizer at a lower pressure, an intermediate condensate is recovered in the vaporizer and cracked or hydrogenated in the coil 18, the products are returned to the vaporizer, vapours are withdrawn at 70 and the residue is submitted to destructive hydrogenation; (2) the feed oil is cracked or hydrogenated in the coil 6, the products are discharged into the vaporizer at a lower pressure, the residue from the vaporizer is heated in an auxiliary still 25, the vapours from the still 25 are cracked or hydrogenated in the coil 18 and the products are returned to the vaporizer, and vapours are withdrawn at 70; the residue from the still 25 may be submitted to destructive hydrogenation; and an intermediate condensate from the vaporizer may be recirculated. In further modifications, (3) the feed oil is admitted to the vaporizer 3 at 31, an intermediate condensate is recovered and cracked or hydrogenated in the coil 6, the products are discharged at a lower pressure into the vaporizer, the residue from the vaporizer is cracked or hydrogenated in the coil 18 and the products are returned to the vaporizer, and vapours are withdrawn at 70; part of the residue may if necessary be withdrawn; (4) the feed oil is admitted to the vaporizer 3, an intermediate condensate is recovered and cracked or hydrogenated in the coil 6, the products are discharged at a lower pressure into the vaporizer, the residue from the vaporizer is heated in the still 25, the vapours from the still are cracked or hydrogenated in the coil 18 and the products are returned to the vaporizer, and vapours are withdrawn at 70; the residue from the still 25 may be submitted to destructive hydrogenation.  In all cases where an p  intermediate condensate from the vaporizer passes through either of the coils 6, 18, it may be introduced partly at the inlet and partly at one or more intermediate points, and the temperature of the products entering the vaporizer may be regulated by admitting intermediate condensate at the outlets of the coils.  In all modifications, the said temperature may be regulated by byepassing a section of each coil.  In all modifications, where applicable, (a) feed oil to be vaporized before cracking or hydrogenation may be first passed under pressure through an auxiliary coil in the furnace 10 or 22, or in a separate furnace as described in Specifications 359,022, 359,023, and 359,025; (b) the still 25 is heated to about 800 DEG  F. at atmospheric pressure or above; (c) intermediate condensate recovered in the vaporizer and recirculated may first be distilled for recovery of fractions which are already sufficiently converted; (d) the light vapours from such distillation may be fractionated separately or with vapours withdrawn from the vaporizer 3, or part or all of the light vapours may be returned to the vaporizer; (e) the vapours withdrawn from the vaporizer 3 are treated in fractionators 71, 72 provided with cooling coils 2<1>, 2<11> in the feed line and with independent cooling coils 73, 74, and condensate from the fractionators may be returned to the vaporizer 3; (f) gases and vapours not condensed with the lightest fractions may be returned to the hydrogenation system, and these gases and vapours, or additional gases such as natural gas or refinery gas, or a mixture of such gases, and steam or catalysts or both, may be subjected to dissociation temperatures, e.g. 1800-2200 DEG  F. before use as hydrogenation gases; (g) the hydrogenating material may be hydrogen, or gases containing or yielding free hydrogen, or it may consist of gaseous hydrocarbons in excess, or of substances capable of liberating hydrogen or gaseous hydrocarbons in excess, e.g. natural gas, coal gas, refinery gas, steam and iron, water and alkali metals or carbide, naphthenes and nickel, hexamethylene and porous porcelain or any combination of these; these <PICT:0359026/III/1> substances and the catalysts or both may be used in suspension or colloidal solution and circulated with the hydrocarbon oil; the hydrogenation gases &c. may be preheated and introduced to the coils 6, 18 at the inlet or at an intermediate point; and the catalysts may be used in the sections 9, 21 of the coils, which may be of larger diameter tubing.  The apparatus is provided with pipes, branches, and control cocks, pumps and check valves permitting working by any of the processes described.  The feed oil is forced by pump 1 through line 2, coils 2<1>, 2<11> in the vapour fractionators 71, 72, coil 3<1> in the vaporizer 3, and thence through line 5 to coil 6 or through branch 31 to the vaporizing chamber 3.  The cracking coils 6, 18 each comprise three sections 7, 8, 9 and 19, 20, 21 in series in different parts of the furnace. Products from the sections 9, 21 pass to the vaporizer 3 through pressure-control valves 11<1>, 23<1> and are separated into vapours (gasoline, naphtha and kerosene), intermediate condensate and residue.  Branch lines 7<1>, 19<1> permit the introduction of oil from an intermediate point of each coil 6, 18.  The vaporizer may be constructed as described in Specification 359,022 (Fig. 5), so that the heavy residue does not mix with the intermediate condensate. Lines 33, 37 with pumps 34, 38 permit the introduction of intermediate condensate from the pan 32 to the inlets of the coils 6, 18, or to intermediate points of the system by branches 35, 36, 39, 40. Branches 52 permit withdrawal of intermediate condensate for distillation, and branches 51, 53 permit return of fractions of the reflux condensate to the lines 33, 37.  Steam may be admitted in this distillation which may be effected as described in Specification 359,025.  The heavy residue from the vaporizer 3 is discharged by a pump 16, through line 15, 17 to the cracking coil 18, or through branch 15<1> for destructive hydrogenation, or through branch 24 to the still 25.  The still 25 is heated by injection of steam at 26, or by direct heat, or by both methods. The residue from the still 25 may be discharged by pump 28 for destructive hydrogenation.  Vapours from the still 25 are discharged by pump 29 to the inlet of the cracking coil 18.  The fractionators 71, 72 for the vapours from the vaporizer 3 are arranged and operated as described in Specifications 359,022, 359,023, 359,024, 359,025, and 359,027.  The fractionators deliver to a condenser 64, separator 109, cooler 110 for the condensate, pump 111 for the gases, purifiers 114, 114<1>, dissociation furnace 115, filters 118, 118<1>, and the gases are finally returned at 112 to the supply 41 for hydrogenation gas, or at 112<1> to the manifold 46. The hydrogenating gas is delivered by pump 43 to heater 44, manifold 46, and branches 47 . . 50 leading to the inlets or to intermediate points of the cracking oils.